Attenuator



l Sept. '7., 1948. J. P. SMITH, JR

ATTENUATOR 2 Sheets-Sheet 2 Filed Nov. l1, 1944 JOHN RSM/TH JR INVENTOR vBY ATTORN EY Patented Sept. 7, 1948 ATTENUATOR John P. Smith, Jr., Verona, N. J., assignor to Daven Company, Newark, N. J., a corporation of New Jersey Application November 11, 1944, Serial No. 562,989

(Cl. 20L-48) 4 claims. 1

This invention relates to attenuators as used in the communications field, and an object of the present invention is to provide an improved construction of attenuators which embodies novel features of construction resulting in a reduction of the manufacturing cost of the device, a simplification of its construction, and provides a structure permitting easy assembly and disassembly With consequent ease of repair or replacement of parts.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing an attenuator of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Figure 1 is an end view of the improved attenuator.

Figure 2 is an end view of the improved attenuator having the dial and turning knob removed.

Figure 3 is a longitudinal section through the attenuator taken on the line 3-3 of Figure 2.

Figure 4 is an end view of the attenuator showing the reverse side of the switch panel.

Figure 5 is an end view of the attenuator showing the contact panel after the removal of the rear cover plate.

Figure 6 is a fragmentary section through the attenuator taken on the line 6-6 of Figure 2.

Figure '7 is a cross section taken on the line 1-1 of Figure 3.

Figure 8 is a detail section taken on the line 8 8 of Figure 2.

Figure 9 is a side elevation of the improved attenuator.

Figure l0 is a detail section taken on the line' I-IU of Figure 5.

Figure 11 is a side elevation partly in section of a modified form of the attenuator.

Figure 12 is a detail plan view of the cover plate employed in the modified form shown in Figure 11.

Referring more particularly to the drawings, the improved attenuator includes a cylindrical housing I, one end of which is closed by an indented closure plate 2. The plate 2 is rigidly attached to the inner surface of the cylindrical housing I at the outer or forward end of the housing by means of its attaching flange 3. A removable cup-like cover 4 forms a closure for the opposite or contact end of the attenuator, and

it has a portion of its side wall slightly offset as shown at 5 to provide a frictionai overlapping, gripping engagement with the adjacent end of the housing I.

The attenuator includes the contact plate G which is made of suitable insulating material and carries a plurality of spaced contacts 1, as is usual in attenuators, which contacts are engaged by the movable contact fingers 8 of the movable contact or switch structure 9. The movable contact or switch structure 9 is attached to a shaft I 0 which extends axially through the housing I. The individual contacts I are connected in the usual manner with the resistance wiring coils II.

The shaft ID projects out of the housing I through the rigid end closure 2 and through the panel board indicated at I3 and through the indicating dial I2. A turning knob I4 is mounted on the shaft I Il for rotating the shaft to move the movable contact fingers 8 over the series of contacts 1. The shaft IU has a detent gear I5 mounted thereon for rotary movement with the shaft. The detent gear I5 is in the form of a disc and is mounted on the shaft outwardly of the rigid end closure 2 so that the gear and its co-operating pawl or detent I6 may be reached for repair or replacement by the removal of the turning knob I4 and the dial I2, and the mounting screws 29 which releases the attenuator from the instrument panel I3.

The pawl or detent I6 is in the form of a bar I1 pivotally connected at I8 to the rigid closure 2. A spring I9 which has one end anchored to the rigid closure 2 is connected to the free end of the lever I 1. An engagement roller 20 is rotatably carried by a head pin 2I which is in turn carried by a pivoted arm I1. The roller 20 engages in the sei-rations in the perimeter of the detent gear I5. To arrest the gear I5, shaft I0, and movable contact unit 8 in selecting positions determined on the dial I2 and in accordance with the positions of the contacts 'I carried by the contact plate B, the rigid closure plate 2 has a stop loop 22 struck outwardly therefrom which is adapted to contact stop loops 23 and 24 which are struck inwardly from the inner surface of the detent I5 to form stops for limiting the rotary movement of the detent, and consequently limiting the rotary movement of the shaft I0 as well as of the movable contact structure 9.

The detent gear I5 has a hub I5 struck therefrom by the formation of the shaft-receiving opening in the gear, and this hub contacting the outer surface of the indented closure plate 2 limits the passage of the shaft I through the closure plate 2 and the contact plate 6, forms a bearing on the shaft for the detent gear and insures proper spacing of the gear relative to the cover plate 2. The shaft l0 is accurately cut to length, and when properly positioned leaves just the proper length projecting through the contact plate 6, so that when the movable contact or switch unit 9 is mounted thereon, the proper tension will be applied to the flexible contact ng'ers 8.

The multiple contact-carrying plate 6, which is formed of insulating material has two hex posts 26 attached thereto which are provided with internally threaded bores. These threaded bores receive screws 21, the heads of which engage in sockets 28 formed in the closure internally 4 proved manner of attaching the contacts 'l to the contact-carrying plate 6 as is clearly shown in Figure 10 of the drawings. The stem 1 of each of the contacts 'I is provided with spiral threads indicated at 'la Which thread into the contactcarrying plate E and thus provide rm connection of the contacts and plates, and substantially prevent looseningof such connections as well as providing a simple connection and easy manner of connection of the contacts to the insulation plate. In Figures 11 and 12 of the drawings, a slight modication of the invention is shown. In this head or plate 2 so as to rigidly connect the coils' Il and the contact-carrying plate E to thehousi ing I to rigidly hold it in position. The rigidly mounted closure plate 2 is also provided with two screw threaded openings 29 which cooperate with screws 3@ to connect the dial l2 to the housing l and to facilitate the mounting of the attenuator on a panel. Thusall that is requiredto mount the attenuator on a panel is merely to place the dial i2 against the outer face of a panel with the attenuator against the inner face of the panel and thread the screws 3i] into the openings 29 thereby permitting attachment of the attenuator to a panel in its assembled form.

The terminal posts 3i which are connected through suitable wiring 32 to the ring contacts 33 and to the coils H are carried by a terminal plate 3d. The terminal plate 34 is of insulating material and is provided with longitudinally` extending grooves 35 in its edges. The housing i is provided with a longitudinally extendingvslitt, the edges of which slidably engage in the grooves 35 in the terminal block34 so that in assembling the attenuator, the entire electrical resistance mechanism which is carried by and assembled Von the contact-carrying plate ii may be slid longitudinally into the housing l with the edges of the slot or slit 36 engaging in the grooves in the ter.- l

minal block 3d, thus not only assuring proper location of all of the parts of the electrical resistance assemblywith respect to the detent l5, but also serving to rigidly hold the terminal block 35i against lateral movement. The removablecuplike cover l is provided with a cut-outsportion (l1 in its inner edge which, when the cover is mounted in position upon the end loi the housing lre ceives the outer end of the terminalY block 34, as clearly shown in Figure 9 of the drawings.' The contact-carrying plate engages against the vouter end of the terminal block 34 and holdsthe terminal block against longitudinal movement.

From the foregoing description taken in connection with the accompanying drawings, it will be apparent that a construction of attenuatorhas been'devised which embodies many novel features of construction so that thev attenuator may fbe quickly and easily assembled and all yof its parts held rigidly Iin position in such manner that i-t may be quickly and easily attached to a panel board, and still access to the various parts of the attenuator which arey apt to need repair or replacement may be readily had, and also thatthe construction is materially simplified'in such manner that its cost will be reduced.y Further, with the present construction, improved protection from dust as Well as improved electrical shielding is afforded.

The present invention also embodies animform, a second cover plate 40 is provided which is placed outwardly of the indented cover plate 2 4andis lattached to the indented cover plate 2 by suitable` screws lli., The secondary cover plate 43 has it portions surrounding the screw receiving openings 42 through which the screws 4I extend indented,l as shown at 43, to permit the heads of the screws 4I to lie flush with the outer surface of the cover plate 40. The cover plate A0 is also provided with spaced openings 44 for receiving therethrough the screws, corresponding to the screws 3i), which are employed to attach the attenuator to the panel board.

It will be understood that the invention `is not to be limited to the-specilic construction or ar rangement of parts shown, but that they may be widely modied with the invention defined by the claims.

What is claimed is: -y

1. Inan attenuator, a housing, a closure head rigidly connected to one end thereof, a removable closure cap over the other end of the housing.

- electricalcurrent resistance-means Within said nected head engaging said terminal plate to hold it against sliding movement, a ,shaft extending axially throughV said closure plate, intosaid housing and'V1 through said contact plate, a detent gear on said shaft outwardly of said closureplate, and means formed-on said detent gear and engaging said closure plate to limit the degreesof insertion of the shaft into the housing. 1

2. In an attenuator, a housing, a contact `plate Within said-housing, a closure plate lrigidlyconnectedto one end ofsaid-` housing;Y connecting posts carried byl said contact plate and npr-'ovided with threaded bores, screws removably carried by said closure plate and threadably engagingin said posts to hold said contact plate-inproperpof sition withsaid housing;v f

3. In an attenuator, a housing, a fixed transverse partition within said housing near the front end thereof, a cutout in the housing to the rear of the partition, a terminal plate-sl-idably mounted on the housing in the cutout, a contact plate abutting the rear end of the terminalv platefand screw-means rigidly connecting the contact plate to the partition. A

4.'In an attenuator, a cylindrical housing, a xed transverse partition -Within saidhousing near the frontend thereof, a transversecontact head longitudinally spaced fromthe partition and to the rear thereof, screw means rigidlygconnectingythe contact head to the-partition, `a rotary shaft havingfa contactl arm for engaging. the contact head extending through the `partition and to the outside of the housing, a detentgear 5 rigidly xed to the shaft adjacent the partition, and means for limiting rotary movement of the detent gear and thus of the shaft and contact arm comprising a pair of angularly spaced abutment members depending from the face of the gear and an abutment member depending from the partition and engageable with the gear abutment members.

JOHN P. SMITH, Jn.

REFERENCES CITED The following references are of record in the le of this patent:

Number Number The Netherlands Oct. 15, 1940 

